Sanda and Marka made a petition to the demon king Hiranyakashipu against Prahlada..... (Bhairo M. 3, p. 1154) Sanda, Marka cried out to the king that Prahlada does not take interest in the studies and they were tired of instructing him. (Bhairo Namdev, p. 1165) Sanda and Marka went to the king and made a complaint and Prahlada was very swiftly called. (Basant Kabir, p. 1194) Sanda and Marka were the two teachers, who were assigned the task of teaching Prahlada.
The devotee (saint) did not listen to them and was always absorbed in devotion. He even talked about the devotion of Vishnu to other fellow-students. See : Prahlada.
1. Kohli,Surindar Singh ed,Dictionary of Mythological References in Guru Granth Sahib 1993